1. Field of the Invention
The present invention relates to a process cartridge and an electrophotographic image forming apparatus to which such a process cartridge can detachably be mounted. Such an "electrophotographic image forming apparatus" may include, for example, an electrophotographic copying machine, an electrophotographic printer (such as a laser beam printer, LED printer and the like), an electrophotographic facsimile and an electrophotographic word processor. The "process cartridge" may incorporate therein an electrophotographic photosensitive member, and a charge means, a developing means or a cleaning means as a cartridge unit which can removably be mounted on an image forming apparatus; may incorporate therein an electrophotographic photosensitive member, and at least one of a charge means, a developing means and a cleaning means as a cartridge unit which can removably be mounted on an image forming apparatus; or may incorporate therein an electrophotographic photosensitive member and at least a developing means as a cartridge unit which can removably be mounted on an image forming apparatus.
2. Related Background Art
In conventional image forming apparatuses using An electrophotographic image forming process, an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally incorporated as a process cartridge which can detachably be mounted to the image forming apparatus. By using such a process cartridge, since the maintenance of the apparatus can be performed by an operator himself without the need for any expert, operability is improved considerably. Thus, the process cartridge has widely been used in image forming apparatuses.
Now, an example of a conventional image forming apparatus (color laser printer) will be described with reference to FIG. 12.
A first charger is constituted by a charge roller 104b which is urged against an image bearing member 104a and to which voltage is to be applied and serves to uniformly charge a surface of the image bearing member 104a prior to image formation. The exposure to the image bearing member 104a is performed by a scanner portion 110 having a laser diode. The laser diode emits laser light in response to an image signal, and the emitted laser light illuminates on a polygon mirror 110a. The laser light reflected from the polygon mirror 110a, which is rotated at a high speed, scans the image bearing member 104a in a generatrix direction thereof. The laser light is collected on the surface of the image bearing member 104a through a focusing lens 110b and a reflection mirror 110c. The surface of the image bearing member (photosensitive drum) 104a is exposed by the laser light corresponding to the image signal, to thereby form a latent image for each color component.
A rotating developing means 105 includes a plurality of developing devices 105M, 105C, 105Y and 105K containing therein magenta color toner, cyan color toner, yellow color toner and black color toner, respectively, which developing devices are rotatably disposed with respect to a shaft 105e. The center of each developing device is rotated synchronously with a rotating gear disposed around a resolving gear, to thereby maintain the posture of the developing device constant. Four developing devices contain the same amount of toners to make the torque distribution to the shaft 105e uniform. In this example, each developing device contains a sufficient amount of toner to print 3000 A3 size sheets can be printed.
During image formation, the developing device 105M (105C, 105Y and 105K) corresponding to the color component of the latent image is brought to be opposed to the image bearing member 104a. At that position, a developing roller 105b of the developing device is positioned in a confronting relation to the image bearing member 104a with a small gap. When the developing device 105M (105C, 105Y and 105K) is shifted to the developing position, the developing roller 105b is connected to a high voltage source of the apparatus so that a developing bias is applied to the developing roller. At the same time, the developing roller is connected to a drive means from a drive source of the apparatus.
By applying the developing bias and the rotational force to the developing roller 105b in this way, the latent image on the image bearing member 104a is developed, to thereby form a toner image.
On the other hand, a sheet supply portion 101 disposed within the apparatus at a lower part thereof serves to supply a transfer material 102 to a transfer drum 103. The transfer materials 102 are housed in a sheet supply cassette 101a. In response to image formation, a sheet supply roller 101b is rotated to pick up the transfer material 102 from the sheet supply cassette 101a, and the picked-up transfer material is supplied to the transfer drum 103.
The transfer material 102 supplied from the sheet supply portion 101 is wound around the transfer drum 103. An electrostatic absorption roller 103g is disposed around the transfer drum 103 to be contacted with and separated from the transfer drum. The electrostatic absorption roller 103g is urged against the transfer drum to pinch the transfer material 102 between the absorption roller and the transfer drum. In this case, by applying a bias between the electrostatic absorption roller 103g and the transfer drum 103, the transfer material 102 is electrostatically adhered to the peripheral surface of the transfer drum 103.
The color toner image formed on the image bearing member 104a is transferred onto the transfer material 102 at the transfer drum 103.
When the transferrring of the magenta toner image is completed, the next developing device 105C is rotated to be brought to the developing position where the developing device is opposed to the image bearing member 104a. By repeating a similar process, the cyan toner image, the yellow toner image and the black toner image are successively transferred onto the same transfer material 102, to thereby form a full-color image. By rotating the transfer drum 103 bearing the transfer material 102 thereon by four revolutions, a full-color image print can be obtained.
A cleaner 104C serves to remove residual toner remaining on the image bearing member 104a and is disposed around the image bearing member 104a at a downstream side of the transfer portion.
The transfer material to which four color toner images were transferred is separated from the transfer drum 103, and the separated transfer material is conveyed to a fixing portion 106. The fixing portion 106 includes a pressure roller 106a, and a fixing roller 106b urged against the pressure roller to apply heat and pressure to the transfer material. While the transfer material is being passed through the fixing portion 106, the color toner images are fixed to the transfer material 102.
After the toner images were fixed to the transfer material at the fixing portion 106, the transfer material is discharged onto a discharge tray 108 by means of a pair of discharge rollers 107.
As mentioned above, in recent years, the image bearing member, the cleaner, the first charger, the developing means and a waste toner box are integrally incorporated into a cartridge which can be detachably mounted to the image forming apparatus. Thus, since the operator himself can mount and dismount the process cartridge with respect to the image forming apparatus, if the toner in the cartridge is completely consumed or if any part of the cartridge reaches its service life, the cartridge can be exchanged for a new cartridge by the operator himself, to thereby facilitate maintenance.
When the service life of the image bearing member is extended and the number of prints is increased, as is in the example shown in FIG. 12, in order to use the developing means, which as the limited toner supplying ability as an independent unit, the process cartridge is divided into a developing cartridge only including the developing means and a drum cartridge unit 104 including the image bearing member 104a, first charger 104b and cleaner 104c, both cartridges being detachably mountable to the image forming apparatus. In this case, the mounting or dismounting of the cartridges and the maintenance of the cartridge can be facilitated, and the cartridges can be used independent from the service lives of the main part thereof (toner consumption or expiration of service life of the part). In such a drum cartridge, the waste toner collected by the cleaner is accumulated in a cleaning container having a volume exceeding the service life of the image bearing member, and, thus, the cleaning container is not filled with the waste toner before the service life of the image bearing member is expired. When the service life of the image bearing member is expired, the drum cartridge is exchanged to a new one.
In the drum cartridge, in order to improve the operability for the operator, i.e., in order to permit exchanging of the other parts or unit such as the developing cartridge along one direction, the drum cartridge is generally mounted on and dismounted from the image forming apparatus along an axial direction.
However, in the above-mentioned conventional drum cartridge, in order to further improve image quality and to further extend the service life, it is required that detailed information regarding the image bearing member and other process units (for example, the difference in feature due to dispersion between the manufacturing accuracy of process units) is supplied to the image forming apparatus to obtain the proper electrophotographic process condition. To this end, recently, there has been proposed a technique in which a memory means (recording medium) is mounted on the cartridge and various information data are stored in the memory means to be supplied to the image forming apparatus through the communication between the cartridge and the image forming apparatus.
In such a cartridge, the memory means and a connector member for connecting the memory means to the image forming apparatus must be mounted at the proper positions in consideration of the inserting direction of the cartridge into the image forming apparatus. On the other hand, in the image forming apparatus and the cartridge used in such an image forming apparatus, in order to mount and dismount the cartridge along the axial direction or longitudinal direction, for example, when the cartridge is exchanged by the operator, it is important to stabilize the holding of the cartridge.